Gamma camera for performing nuclear mammography imaging

ABSTRACT

A gamma camera for use in a molecular imaging system includes a housing, a cadmium zinc telluride (CZT) camera disposed within the housing, and at least one retractable wall coupled to the housing and adapted to secure an anatomy of interest in a field-of-view of the gamma camera. The gamma camera also includes a chamfered edge to enable the gamma camera to contact a second gamma camera when the gamma camera is positioned in an L-mode imaging configuration.

BACKGROUND OF THE INVENTION

This invention relates generally to medical imaging systems, and moreparticularly to a system and method for performing nuclear mammographyimaging.

Different systems and methods for performing mammography imaging areknown. For example, one conventional imaging system is a film screenmammography imaging. This type of mammography imaging system usestransmitted x-rays to produce an image of the breast. During the imagingprocedure, a compression force is applied to a breast to improve imagequality by reducing a thickness of the breast thereby spreading thebreast tissue over a larger area. The reduction in the breast thickness,and spreading the breast over a larger area, facilitate reading of theprojection radiographs, because the amount of “overlapping structures”within the imaged breast is minimized in the projection radiograph. Thistype of mammography imaging may not perform satisfactory imaging inwomen with dense breasts. Moreover, some patients may experiencediscomfort due to the compression force applied to the breast and lowerpatient acceptance may result in missed examinations, thereby possiblyincreasing the patient's risk that a serious medical condition may notbe detected in a timely fashion.

Another conventional imaging system utilizes diagnostic nuclear imagingto identify radionuclide distribution in a subject, such as a humanpatient. Typically, one or more radiopharmaceuticals or radioisotopesare injected into the subject. The imaging system includes conventionalgamma detectors that are placed adjacent to a surface of the subject tomonitor and record emitted radiation. The monitored radiation data isreconstructed and/or displayed into an image representation of theradiopharmaceutical distribution within the subject. Generally thespatial resolution of a gamma detector degrades with increasing distancebetween the imaged area/organ and the detector. Therefore, it isdesirable to place the gamma detector as close as possible to thepatient to facilitate minimizing the loss of image resolution. It isalso desirable to place the detector so that only the breast and noother confounding structures are in the imaging field of view. However,the size of these conventional detectors allows only anterior-posteriorimaging with sufficient proximity to the breast, and in this case thebackground activity from the thorax structures including the heartdegrade the sensitivity for finding small lesions of the breast.

Sometimes, small cameras are used with other views to overcome theprevious problem. For example the medial lateral oblique view may beused or a compression force may be used. For example, when utilizing onecompact imaging system to image a patient's breast, a compression forceis applied to the breast to secure the breast during imaging process.However, similar to the film screen mammography imaging system thecompression force may cause some patients to experience discomfort andmay not schedule any future examinations, thereby possibly increasingthe patient's risk that a serious medical condition may not be detectedin a timely fashion. Thus there is a need to avoid compression in animaging modality. Furthermore, there is a need to contain the breast inthe field of view of dedicated compact cameras configured for breastimaging, for example in medial lateral oblique views where gravity maypull the breast out of the field of view.

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment, a gamma camera is provided. The gamma camera includesa housing and a camera disposed within the housing. The gamma cameraalso includes a retractable wall or structure coupled to the housing,the retractable wall or structure being fully retracted into the housingor detachable from the housing, or otherwise removed from activation ina first imaging mode and extending from the housing or activated toretain the subject within the field of view in a different secondimaging mode.

In another embodiment, another gamma camera is provided. The gammacamera includes a housing comprising a chamfered edge to enable thegamma camera to contact a different second gamma camera when the gammacamera is positioned in an L-mode imaging configuration, a cadmium zinctelluride (CZT) camera disposed within the housing, and at least oneretractable wall coupled to the housing and adapted to secure an anatomyof interest in a field-of-view of the gamma camera.

In a further embodiment, a method of fabricating a gamma camera isprovided. The method includes fabricating a housing that includes afirst side, a second side, a third side, a fourth side, and an openingdefined by the first, second, third, and fourth sides, installing acadmium zinc telluride (CZT) camera within the housing opening, andinstalling at least one retractable wall within the housing, theretractable wall adapted to secure an anatomy of interest in afield-of-view of the gamma camera.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a front perspective view of an exemplary molecular imagingsystem in accordance with an embodiment of the present invention.

FIG. 1B is another front perspective view of an exemplary molecularimaging system shown in FIG. 1 including a patient positioned in asecond imaging position in accordance with an embodiment of the presentinvention.

FIG. 2 is a side view of the imaging system shown in FIG. 1.

FIG. 3 is a schematic illustration of the exemplary molecular imagingsystem shown in FIGS. 1 and 2 in accordance with an embodiment of thepresent invention.

FIG. 4A is a front perspective view of a portion of the molecularimaging system shown in FIGS. 1 and 2 in accordance with an embodimentof the present invention.

FIG. 4B is a top view of a portion of the molecular imaging system shownin FIG. 4A.

FIG. 5A is a front perspective view of an exemplary pressure plate thatmay be used with the imaging systems described herein in accordance withan embodiment of the present invention.

FIG. 5B is a front perspective view of another exemplary pressure platethat may be used with the imaging systems described herein.

FIG. 5C is a front perspective view of another exemplary pressure platethat may be used with the imaging systems described herein.

FIG. 5D is a front perspective view of another exemplary pressure platethat may be used with the imaging systems described herein.

FIG. 5E is a front perspective view of another exemplary pressure platethat may be used with the imaging systems described herein.

FIG. 6A is a back perspective view of the gamma camera shown in FIGS. 1and 2 in accordance with an embodiment of the present invention.

FIG. 6B is a front view of the gamma camera shown in FIG. 6A.

FIG. 7 is a perspective view of a portion of the imaging system shown inFIGS. 1A and 1B in a first operational configuration.

FIG. 8A is a front perspective view of the imaging system shown in FIGS.1A and 1B in another exemplary operational position in accordance withan embodiment of the present invention.

FIG. 8B is a front view of the imaging system shown in FIGS. 1A and 1Bin another exemplary operational position.

FIG. 8C is a side view of the imaging system shown in FIGS. 1A and 1B inanother exemplary operational position.

FIG. 8D is a front view of the imaging system shown in FIGS. 1A and 1Bin another exemplary operational position.

FIG. 8E is a side view of the imaging system shown in FIGS. 1A and 1B inanother exemplary operational position.

FIG. 9A is perspective view of the gamma camera shown in FIG. 8A in afirst operational position.

FIG. 9B is perspective view of the gamma camera shown in FIG. 9A in asecond operational position.

FIG. 10A is a schematic illustration of a first exemplary collimatoralignment.

FIG. 10B is a schematic illustration of a second exemplary collimatoralignment.

FIG. 11 is a front view of an exemplary calibration position.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments of the invention provide a system and method forperforming molecular imaging of an anatomy of interest. A technicaleffect of the various embodiments is to provide a molecular imagingsystem that is configured to perform imaging optionally in both anH-mode and an L-mode configuration. The molecular imaging system is alsoconfigured to identify tumors or lesions during or after an imagingexamination and to facilitate performing a biopsy of the identifiedtumors or lesions in the anatomy of interest.

FIG. 1A is a front perspective view of an exemplary molecular imagingsystem 10 illustrating a patient positioned for imaging in a firstimaging position. FIG. 1B is a front perspective view of the imagingsystem 10 illustrating a patient positioned for imaging in a secondimaging position. FIG. 2 is a side view of the imaging system 10 shownin FIGS. 1A and 1B. In the exemplary embodiment, the molecular imagingsystem 10 is configured as a standalone molecular imaging system. Themolecular imaging system 10 may be mounted stationary by coupling thesystem 10 to a floor. Optionally the system 10 may include wheels (notshown) to enable system 10 to be portable. The molecular imaging system10 includes a housing 11 and a gantry 12 that is rotatably coupled tothe housing 11 via a carriage 13. The imaging system 10 also includes afirst gamma camera 20, a second gamma camera 22, and a biopsy needlepositioning device 80 that are coupled to the gantry 12. To facilitateimaging in various configurations, the gantry 12 is rotatable around thehousing 11.

Referring to FIG. 2, the gantry 12 is coupled to the housing 11 via thecarriage 13. The gantry 12 is rotatably coupled to the carriage 13 via apivot device 15. During operation, the carriage 13 is configured to moveup and down along a pair of rails 17 to enable a patient to be imaged ina standing or sitting or bed position. Moreover, since the gamma cameras20 and 22 and the biopsy needle positioning device 80 are rotatablycoupled to the gantry 12 which is coupled to the carriage 13, the gammacameras 20 and 22 and the biopsy needle positioning device 80 are alsomoveable along the pair of rails 17.

The gantry 12 is configured to pivot to a plurality of radial positionsto position the gamma cameras 20 and 22 for imaging a patient. After thegantry 12 is positioned, the gantry 12 remains stationary during theimaging process as discussed below. Additionally, the first and secondgamma cameras 20 and 22 are each positionable to perform imaging of ananatomy of interest 24 that is positioned between the first and secondgamma cameras 20 and 22. During operation, the patient may be imaging bypositioning the patient in a sitting position as shown in FIG. 1A. Inthis imaging position, the gamma cameras 20 and 22 are adjustedvertically until the height of the gamma cameras 20 and 22 aresufficient to enable the patient to place a breast on the gamma cameras20 and 22. As shown in FIG. 1B the patient may also be imaging in areclined or laying down position. In this case, the patient ispositioned on a table in front of the gamma cameras 20 and 22. The gammacameras 20 and 22 are then raised or lowered, via the gantry 12, thecarriage 13, and the pair of rails 17, to enable the patient to place abreast on the gamma cameras 20 and 22. More specifically when the gammacameras 20 and 22 are positioned at the proper imaging height, thepatient is moved, via the movable table into the field of view of thegamma cameras.

FIG. 3 is a schematic illustration of an exemplary workstation 14 thatmay be included with system 10 to control image reconstructionprocesses. In the exemplary embodiment, the operator workstation 14 iscoupled to the housing 11, and thus is also coupled to the gantry 12 andthe first and second gamma cameras 20 and 22. In one embodiment, thegantry 12 is coupled to the operator workstation 14 via a communicationlink 26 (e.g., a hardwired communication link or wireless communicationlink). Optionally, the operator workstation 14 may be constructed aspart of the housing 11.

The operation of the molecular imaging system 10 is controlled by theoperator workstation 14. As shown in FIG. 2, the operator workstation 14includes a general purpose or a dedicated computer 30, an input device32, and a display 34. The computer 30 may include a processor 36 and amemory device 38. The memory device 38 may be embodied as Random AccessMemory (RAM) and/or Read Only Memory (ROM). The computer 30 further mayinclude a storage device 40. The storage device 40 may be embodied as ahard disk drive or a removable storage such as a floppy disk drive,optical disk drive, USB memory and the like. The storage device 40 mayalso be other similar means for loading computer programs or otherinstructions into the computer 30.

As used herein, the term “computer” may include any processor-based orprocessor-based system including systems using controllers, reducedinstruction set circuits (RISC), application specific integratedcircuits (ASICs), logic circuits, and any other circuit or processorcapable of executing the functions described herein. The above examplesare exemplary only, and are thus not intended to limit in any way thedefinition and/or meaning of the term “computer”.

As discussed above, the operation of the molecular imaging system 10 iscontrolled from the operator workstation 14. More specifically theprocessor 36 executes a set of instructions that are stored in one ormore storage elements, e.g. the memory device 38 and/or the storagedevice 40. The set of instructions instruct the processor 36 to performvarious functions. One such exemplary function includes acquiringemission data from the gamma cameras 20 and 22 that is acquired from theanatomy of interest 24. More specifically, the set of instructions mayinclude various commands that instruct the computer 30 as a processingmachine to perform specific operations such as the methods and processesof the various embodiments of the invention. For example, one set ofinstructions may instruct the processor 36 to perform a scan of theanatomy of interest 24 using the first and second gamma cameras 20 and22 to acquire emission data. Another set of instructions may instructthe processor 36 to transmit the emission data from the first gammacamera 20 to the communication link 26 via a communication link 42 andto transmit emission data from the second gamma camera 22 to thecommunication link 26 via the communication link 42. The set ofinstructions may further include instructions to instruct the processor36 to utilize the emission data to reconstruct an image of the anatomyof interest 24 and display the reconstructed image on a display e.g. thedisplay 34.

The set of instructions may be in the form of a software program. Thesoftware may be in various forms such as system software or applicationsoftware. Further, the software may be in the form of a collection ofseparate programs, a program module within a larger program or a portionof a program module. The software also may include modular programmingin the form of object-oriented programming. The processing of input databy the processing machine may be in response to user commands, or inresponse to results of previous processing, or in response to a requestmade by another processing machine. As used herein, the terms “software”and “firmware” are interchangeable, and include any computer programstored in memory for execution by a computer, including RAM memory, ROMmemory, EPROM memory, EEPROM memory, and non-volatile RAM (NVRAM)memory. The above memory types are exemplary only, and are thus notlimiting as to the types of memory usable for storage of a computerprogram.

During operation, the gamma cameras 20 and 22 are configured to berepositioned from a first operational positional to a second operationalposition. For example, FIG. 4A is a perspective view of the gantry 12shown in FIGS. 1A and 1B including one such exemplary reposition device.FIG. 4B is a top view of the gantry 12 shown in FIGS. 1A and 1Bincluding one such exemplary positioning device. As shown in FIG. 4A, inone exemplary embodiment, the gamma camera positioning device isembodied as a motor 54 that is coupled to and moves the gamma camera 20around a radial axis. In this exemplary embodiment, the imaging system10 also includes a motor 55 that is coupled to the gamma camera 22 andmoves the gamma camera 22 around a radial axis. In another exemplaryembodiment, the gamma cameras 20 and 22 may be repositioned manually bythe operator. More specifically the gamma camera 20 and 22 may each beweighted and balanced and to enable the operator to disengage amechanical or electromechanical clutch to permit manual repositioning ofeach respective gamma camera.

Referring again to FIG. 4A, the gantry 12 includes a first opening 62and a second opening 64. Moreover, gamma camera 20 includes a mountingbracket 66 and gamma camera 22 includes a mounting bracket 68. Themounting brackets 66 and 68 are each coupled at a first end to the gammacamera 20 and 22, respectively. The mounting bracket 66 extends throughthe first opening 62 and the mounting bracket 68 extends through thesecond opening 64. The mounting brackets 66 and 68 are each anchoredwithin the gantry 12 to enable each of the gamma cameras 20 and 22 to berepositioned. More specifically, the mounting brackets 66 and 68 enableeach of the respective gamma cameras 20 and 22 to be positioned toperform imaging of the anatomy of interest 24.

In the exemplary embodiment, the mounting brackets 66 and 68 also enablethe respective gamma cameras 20 and 22 to move in an X-direction 74, aY-direction 76, and optionally in a Z-direction 78. Moving the gammacameras 20 and 22 in the X-direction facilitates raising and loweringthe gamma cameras 20 and 22, via the gantry 13, to enable the molecularimaging system 10 to accommodate a range of standing patients and/orsitting and/or reclining patients. Moving the gamma cameras 20 and 22 inthe Y-direction, via the gantry 12, facilitate moving the gamma cameraseither closer together or further apart to enable the molecular imagingsystem 10 to accommodate different anatomies of interest having varioussizes. As such, the gamma cameras 20 and 22 are each positionable alongtwo or three linear and separate or linear and common axes. Moreover,the gamma cameras 20 and 22 and the gantry 12 are each rotatable toaccommodate different imaging modes and patient anatomies.

As discussed above, the gamma cameras 20 and 22, via the mountingbrackets 66 and 68, may be either manually operated or motorized toenable the respective gamma cameras 20 and 22 to each be rotated ineither a clock-wise direction 70 or a counter-clockwise direction 72. Assuch, the gamma cameras 20 and 22 may be repositioned to perform imagingin an L-mode configuration, an H-mode configuration, or any otherconfiguration between the L-mode and H-mode configurations. The gammacameras 20 and 22 may be in contact or separated and may have anglesfrom 0° (parallel, in contact on an edge and beside each other) to 90°(contacting on and edge) to 180° (i.e. facing each other and nottouching) with respect to each other.

In the L-mode configuration, shown in FIG. 1A, the gamma camera 20 issubstantially perpendicular to the gamma camera 22. In the H-modeconfiguration, shown in FIG. 6, the imaging face of the first gammacamera 20 is approximately parallel to and facing the imaging face ofthe second gamma camera 22. It should be realized that although only twooperational modes are discussed, e.g. L-mode and H-mode, the gammacameras 20 and 22 may be positioned in a plurality of operationalpositions within each of the L-mode and H-mode positions. For example,as shown in FIG. 1A, the gamma camera 20 is positioned at a right anglewith respect to the gamma camera 22. As such, the imaging face of thefirst gamma camera 20 is disposed at an angle that is approximately 90(right angle) degrees from the imaging face of the second gamma camera22. In the exemplary embodiment, the molecular imaging system 10 mayalso be configured in the H-mode as discussed in further detail below.In all cases the precise relative position of the detectors can be knownthrough previous calibration or mechanical, or electrical measurement orsensors, mounted on or mounted remotely from the system 10. Thepositions may be automatically recorded and used to present imagesand/or combine views, or guide biopsy with respect to featuresdetectable in either or both detectors.

Referring again to FIG. 4A, in the exemplary embodiment the molecularimaging system 10 also includes the biopsy needle positioning device 80(also shown in FIGS. 1A and 1B) that is coupled to the gantry 12. Thebiopsy needle positioning device 80 may reposition a biopsy needle 82(shown in FIGS. 1A and 1B) to a first position in the L-modeconfiguration (shown in FIGS. 1A and 1B) and to a second differentposition in the H-mode configuration (shown in FIGS. 8A-8C and discussedin more detail below). Referring again to FIG. 4A, the biopsy needlepositioning device 80 includes a mounting plate 84 and a pressure plate86 that is coupled to the mounting plate 84. In the exemplaryembodiment, the mounting plate 84 is substantially perpendicular to thepressure plate 86. The mounting plate 84 includes a plurality ofchannels 88 that enable the biopsy needle 82 to move in the X-direction74 and the Y-direction 76. Moreover, the biopsy needle 82 is alsorepositionable along the Z-axis. For example, the biopsy needle 82 maybe moved along the Z-axis closer to or further from the gantry 12 toenable larger and smaller anatomies of interest to be biopsied.

The biopsy needle positioning device 80 is also movable along an arcuatepath 90. For example, during an L-mode imaging procedure, the biopsyneedle positioning device 80 is movable along the arcuate path 90 toenable the biopsy needle 82 to be positioned at an approximately 0degrees wherein the biopsy needle 82 is positioned at a centerlinebetween the first and second gamma cameras 20 and 22. Additionally, thebiopsy needle positioning device 80 is movable along the arcuate path 90to enable the biopsy needle 82 to be positioned at a approximately 45degrees from the centerline 92 shown in FIG. 1A, e.g. the biopsy needleis approximately parallel to either the gamma camera 20 or the gammacamera 22 when the molecular imaging system 10 is operated in the L-modeconfiguration. Any other line of approach to biopsy a lesion within thebreast volume is also possible with computer positioning computation andguidance or control or visualization of the entry path superimposed onthe gamma camera images of the breast and the target tissue

As discussed above, and shown in FIG. 4A, the biopsy needle positioningdevice 80 also includes the penetrable pressure plate 86. In the L-modeconfiguration, the pressure plate 86 and the gamma cameras 20 and 22together form a substantially triangular anatomy capture region 87(shown in FIGS. 1A and 1B). The anatomy capture region 87 is selectivelysized to receive the anatomy of interest 24 therein. For example, thesize of the anatomy capture region 87 may be increased to facilitateimaging a larger anatomy of interest by repositioning the gamma cameras20 and 22 and the pressure plate 86 to form a larger triangular anatomycapture region 87. Moreover, to facilitate imaging a small anatomy ofinterest 24, the gamma cameras 20 and 22 and the pressure plate 86 maybe repositioned to form a smaller triangular anatomy capture region 87.The pressure plate 86 may also be curved and the anatomy capture regionaccordingly different. As well the plate may be a constructed from foamor other tensile or stiff material to accomplish the same function.

Referring again to FIG. 4B, the pressure plate 86 includes a pluralityof penetrations, pores, virtual openings as between the weave of afabric or openings 96. In the exemplary embodiment, the openings 96 arearranged in rows along the Y-axis and columns along the Z-axis. Eachopening 96 has a diameter that is sized to enable at least a portion thebiopsy needle 82 to be inserted therethrough. In the exemplaryembodiment, the pressure plate 86 is deformable to enable anatomies ofinterest having different sizes to be captured as is discussed in moredetail below. In the exemplary embodiment, the deformable immobilizingpressure plate 86 is positioned between the first and second gammacameras 20 and 22 to secure the anatomy of interest 24 in asubstantially fixed or immobilized position during the imagingprocedure.

FIGS. 5A-5E illustrate several embodiments of exemplary pressure platesthat may be used in lieu of pressure plate 86. For example, FIG. 5A is afront perspective view of an exemplary pressure plate 500 that may beused with the imaging systems described herein. In the exemplaryembodiment, the pressure plate 500 is a removable and replaceablepressure plate 500 that has a substantially planar surface 502. Thepressure plate 500 also includes a plurality of openings 504 that aresized to receive the biopsy needle 82 therethrough. The pressure plate500 also has a width 506 that is selected to form a smaller anatomycapture region to enable a less dense breast to be imaged. Moreover, tofacilitate imaging a denser or larger anatomy of interest 24, a secondreplaceable pressure plate 508 may be utilized. The second pressureplate 508 is substantially similar to the pressure plate 500, however awidth 510 of the second pressure plate 508 is greater than the width 506of the pressure plate 500 to enable a denser breast to be imaged.Specifically, the wider pressure plate 508 forms a larger capture regionto enable a larger or denser breast to be imaged. It should be realizedthat although only two replaceable pressure plates are illustrated, thata variety of pressure plates having various widths may be utilized toimage a variety of breasts of varying sizes and density. The pressureplates 500 and 508 are coupled to the imaging system in the same manneras discussed above regarding pressure plate 86.

FIG. 5B is a front perspective view of another exemplary pressure plate520 that may be used with the imaging systems described herein. In theexemplary embodiment, the pressure plate 520 is a removable andreplaceable pressure plate that has a substantially curved surface 522.The pressure plate 520 also includes a plurality of openings 524 thatare sized to receive the biopsy needle 82 therethrough. The pressureplate 502 also has a width 526 that is selected to form a smalleranatomy capture region to enable a less dense breast to be imaged.Moreover, to facilitate imaging a denser or larger anatomy of interest24, a second replaceable pressure plate 528 having a curved surface 522may be utilized. The second pressure plate 528 is substantially similarto the pressure plate 520, however a width 530 of the second pressureplate 528 is greater than the width 526 of the pressure plate 520 toenable a denser breast to be imaged. Specifically, the wider pressureplate 528 forms a larger capture region to enable a larger or denserbreast to be imaged. It should be realized that although only tworeplaceable pressure plates are illustrated, that a variety of pressureplates having various widths may be utilized to image a variety ofbreasts of varying sizes and density. The pressure plates 520 and 528are coupled to the imaging system in the same manner as discussed aboveregarding pressure plate 86.

FIG. 5C is a front perspective view of another exemplary pressure plate540 that may be used with the imaging systems described herein. In theexemplary embodiment, the pressure plate 540 is a removable andreplaceable pressure plate that has a flexible portion 542. Morespecifically, the pressure plate 540 includes two substantially rigidside member 544 and a flexible portion 546 that is coupled between andto the rigid side members 544. The pressure plate 540 also includes aplurality of openings 548 that are sized to receive the biopsy needle 82therethrough. The pressure plate 540 also has a width 550 that isselected to enable any size breast to be imaged. As shown in the FIG.5C, during operation, the flexible portion 546 deforms or flexes whenplaced in contact with a breast to be imaged. The flexing or deformingmovement enables the pressure plate to immobilize any size breast duringthe imaging procedure. The pressure plates 540 is coupled to the imagingsystem in the same manner as discussed above regarding pressure plate86.

FIG. 5D is a front perspective view of another exemplary pressure plate550 that may be used with the imaging systems described herein. In theexemplary embodiment, the pressure plate 550 is a removable andreplaceable pressure plate. The pressure plate 550 includes a main bodyportion 552 and at least two extensions 554 that are coupled to the bodyportion 552. As shown in FIG. 5D each extension is mounted to a side ofthe body portion 552 to either increase or decrease a width 556 of theoverall pressure plate 550. More specifically, the image a smaller orless dense breast, the pressure plate 550 may be utilized without theextensions 554. However, to image a larger or denser breast, theextensions 554 may be coupled to the sides of the body portion 552thereby increasing the overall width of the pressure plate 550 to enablelarger breasts to be imaged. It should be realized that a variety ofextensions, each having a predetermined width may be utilized to definea pressure plate having a predetermined width based on the size of thebreast to be imaged. The body portion 552 and the extensions 554 eachinclude a plurality of openings 558 that are sized to receive the biopsyneedle 82 therethrough. Moreover, the openings 558 in the extensions aresubstantially aligned with the openings 558 in the body portion. Thepressure plate 550 is coupled to the imaging system in the same manneras discussed above regarding pressure plate 86.

FIG. 5E is a front perspective view of another exemplary pressure plate560 that may be used with the imaging systems described herein. In theexemplary embodiment, the pressure plate 560 is a removable andreplaceable pressure plate. The pressure plate 560 includes a main bodyportion 562 and at least two telescopic extensions 564 that are coupledto the body portion 562. As shown in FIG. 5E each extension extends froma recess 566 that is formed in a respective side of the body portion562. During operation, to image a smaller or less dense breast, theextensions 564 may be fully retracted into the body portion 562.However, to image a larger or denser breast, the extensions 564 are atleast partially extended from the body portion 562. More specifically, awidth 568 of the pressure plate 560 may be adjusted by either extendingor retracting the extensions 564. In this manner, a larger variety ofbreasts of different sizes may be imaged without removing or replacingthe pressure plate. It should be realized that a variety of extensions564, each having a predetermined width may be utilized to define apressure plate 560 having a predetermined width based on the size of thebreast to be imaged. The body portion 562 and the extensions 564 eachinclude a plurality of openings 570 that are sized to receive the biopsyneedle 82 therethrough. Moreover, the openings 570 in the extensions aresubstantially aligned with the openings 570 in the body portion. Thepressure plate 560 is coupled to the imaging system in the same manneras discussed above regarding pressure plate 86.

During the imaging operation, the molecular imaging system 10 isconfigured to enable the anatomy of interest 24 to be imaged to detectlesions, tumors, or other medical information. In the exemplaryembodiment, the anatomy of interest 24 is a breast of a human patient.Moreover, in the exemplary embodiment, the patient is in a sittingposition upon a chair and the breast is disposed between, and restingupon, the gamma cameras 20 and 22. During operation, aradiopharmaceutical that concentrates in a predetermined region of thebreast is injected into a patient. The patient is then seated at themolecular imaging system 10 such that the patient's breast is positionedbetween the pair of gamma cameras 20 and 22. As discussed above, themolecular imaging system may be configured in an L-mode configuration,an H-mode configuration, or any other configuration between the L-modeand H-mode configurations. The gamma cameras 20 and 22 are then adjustedto capture the breast and immobilize it for the duration of the scan. InH mode CC view the breast is captured from top and bottom with thecamera surfaces. In H mode ML or MLO the assistance of the retainingplate may assist to keep the tissue within the field of view from below.In L mode the biopsy plate or equivalent may be used to capture withimmobilization.

In the exemplary embodiment, the tissue capture is accomplished with aimmobilizing force that is less than a compression force applied to thebreast during a conventional mammography imaging procedure. For example,as discussed above, conventional mammographic imaging systems apply acompression force to the breast to flatten the breast, spreading out thetissue and separating the structural features, and thereby improvingimage quality. The conventional mammographic imaging system may apply asufficient compression force to the breast to cause the patientdiscomfort. Whereas, during operation of the molecular breast imagingsystem 10 an immobilizing force is applied to the breast to ensure thatthe breast is stationary during the imaging process. Moreover, theimmobilizing force is selected to ensure that the breast is disposed onthe gamma cameras 20 and 22 and the tissue is entirely within thecapture region. In the exemplary embodiment, the immobilizing forceselected is sufficient to maintain the breast in a stationary positionagainst the gamma cameras 20 and 22. Moreover, the immobilizing force isless than the compression force applied by a conventional imaging systemto perform mammographic imaging. Moreover tissue spreading to separatestructural features is not required for the molecular breast imagingsystem 10 since the said structural features are not present inmolecular breast imaging. Moreover, a compression force would oftenresult in tissue being forced out of the field of view and failure ofthe molecular breast imaging system to detect disease. Therefore, usingan immobilizing force facilitates providing a more comfortableexamination and while still providing image quality sufficient tosignificantly enhance the performance of tumor and lesion detectioncompared to conventional mammography.

After the immobilizing force is applied to the anatomy of interest 24,the gamma cameras 20 and 22 are activated to generate an image of theanatomy of interest. In the exemplary embodiment, gamma camera 20produces a first medical image and gamma camera 22 produces a differentsecond medical image. The medical images may be viewed one at a time, orside-by-side on the display 34. In another embodiment, the processor 36includes instructions to combine the images. More specifically, theprocessor 36 may include instructions to register the first image andthe second image to generate a combined image. In one embodiment, thecombined image is a two-dimensional image of the anatomy of interest 24.Optionally, the combined image is a three-dimensional image of theanatomy of interest. Moreover, in the L-mode configuration, themolecular imaging system 10 generates two views of the anatomy ofinterest that are acquired from two non-colinear projection angles togenerate a projection dataset of the volume of anatomy of interest 24.The two views represent the projection dataset. The collected projectiondataset is then utilized to generate a three-dimensional dataset,representative of the three-dimensional representation of imaged anatomyof interest 24. In another embodiment, the projection dataset isdeconvolved using the data acquired from the two gamma cameras 20 and 22to ascertain a true planar projected size, position, and strength of thelesion or tumor without the distorting effects of the detectorresolution function. Deconvolution may for example be achieved byrefining an initial guess based on iterative forward projection usingthe collimator response function to obtain a test projection dataset andback projection of the difference between the test projection datasetand the measured projection dataset. Deconvolution may also be achievedby comparing the 6 values of diameter and position measured by the 2cameras to a stored lookup table of lesion size, radioactivity strength,and position. Alternatively partial lookup and partial iterative can becombined to ascertain the lesion size, radioactivity strength, andposition. The improved lesion image obtained by removal of thecollimator response function is used to improve decisions of whether anobserved imaging feature is a statistically significant region of traceruptake as opposed to a background noise fluctuation, as well as to moreaccurately target the center of the lesion with the biopsy needle. Theinformation of the absolute lesion uptake ratio (compared to normaltissue) may also prove to be usefully correlated to the tissue pathologyin the future.

FIG. 6A is a perspective view of the gamma camera 20 shown in FIGS. 1-1Aand 1B. FIG. 6B is a front view of the gamma camera 20 shown in FIG. 6A.In the exemplary embodiment, gamma camera 20 is substantially similar tothe gamma camera 22. As such, the gamma camera 20 and the gamma camera22 include an external housing 110. In the exemplary embodiment, thehousing 110 is substantially square or rectangular and includes a firstside 120, a second side 122 that is substantially perpendicular to thefirst side 120, a third side 124 that is approximately parallel to thesecond side 122, and a fourth side 126 that is substantially parallel tothe first side 120. Moreover, the housing 110 includes a first surface128 and an opposing second surface 130. In the exemplary embodiment, thefirst surface 128 is a gamma emission detecting surface and is referredto herein as the detecting face 128. The first side 120 is configured toenable the first gamma camera 20 to be reproducibly mounted to thegantry 12 via the mounting bracket 66 as shown in FIG. 2 and discussedabove. Additionally, the mounting bracket 68 enables the first side 120of the second gamma camera 22 to be reproducibly mounted to the gantry12. Side 126 may include a chamfer if the structure of the camera islarger in the plane of 156 than the parallel plane in the Field of view160.

Referring again to FIG. 6A, in one embodiment, the first side 120includes at least two openings 132 that are adapted to receive a bolt133 at least partially therein. The combination of the bolts 133 and theopenings 132 enable the mounting brackets 66 and 68 to be coupled to thegamma camera 20 and gamma camera 22, respectively, and thus also becoupled reproducibly to the gantry 12. Optionally, other mounting guidemechanisms such as pins or edges and latches or interlocks may be usedto reproducably mount the detectors.

The gamma camera 20 also includes a Cadmium Zinc Telluride (CZT)detector array 140, an electronics device 142, and a collimator 144. Asshown in FIG. 5, the gamma camera 22 also includes a Cadmium ZincTelluride (CZT) detector array 141, an electronics device 143, and acollimator 145. More specifically, the detector arrays 104 and 141 maybe fabricated of a compact Cadmium Zinc Telluride (CZT) semiconductor,or alternative compact detector such as from CdTe or HgI or CsI orothers. A photoconduction process within the CZT semiconductor generateselectron-hole pairs in an interaction with gamma photons. The electronsand/or holes move toward respective electrodes of the electronics device142/143 generating an output electrical signal comprising photon count,position, and energy data.

During operation, the patient is injected with a radiopharmaceuticalthat concentrates in known regions of the anatomy of interest and emitsemission gamma rays. Subsequently, the anatomy of interest, in thiscase, the breast, 24 is positioned between the gamma cameras 20 and 22as discussed above. The gamma rays emitted from the anatomy of interest24, are collimated by the collimators 144/145 to produce an image. Thecollimated gamma rays are then detected by the respective CZT detectorarrays 140/141. The output from the CZT detector arrays 140/141 areinput to the respective electronics devices 142/143 to be output as anelectrical signal comprising photon count, position, and energy data.The outputs from the electronics devices 142/143 are used to reconstructor generate an image of the anatomy of interest 24.

Referring to FIG. 7, as discussed above in the L-mode configuration itis desirable to position the gamma cameras 20 and 22 as close togetheras possible to improve image quality, and to position the gamma cameras20 and 22 as close to the patient as possible to facilitate minimizingthe loss of resolution. For example, conventional detectors include ahousing that limits the distance the detectors may approach during theimaging process. Specifically the field of view of conventionaldetectors is typically separated by a distance that is at least 5millimeters and may be as high as 7 cm. As such, conventional detectorsmay be unable to identify lesions or tumors that are located in the gapdefined between the conventional detectors. Furthermore they may beunable to see with both cameras a lesion that is located on the surfaceof the anatomy of interest and therefore close to one camera and out ofthe field of view of the other camera.

In the exemplary embodiment, to improve image quality and to facilitateeliminating the gap between conventional detectors, at least a portionthe housings of gamma cameras 20 and 22 are chamfered to enable thegamma camera 20 to contact the gamma camera 22 during the imagingprocedure and for the close region of each camera to be seen by theother camera as well. More specifically, referring again to FIG. 6A,each of gamma cameras 20 and 22 include at least two chamfered ortapered edge 150 and 152, respectively, that enables the gamma camera 20to contact the gamma camera 22, when the gamma cameras 20 and 22 arearranged in the L-mode configuration. More specifically, in theexemplary embodiment, one chamfered edge 150 is formed on the secondside 122 of the gamma camera 20 and a second chamfered edge 152 isformed in the third side 124 of the gamma camera 20. The chamfered edges150/152 each extend along the length of the sides 122/124 and alsoextend from a horizontal line 156 to the detecting face 128 of the gammacamera 20. In the exemplary embodiment, the chamfered edges 150/152 aredisposed at the mating edges of each of the gamma cameras such that eachgamma camera can view tissue within the first mm of the surface of theopposing gamma camera. The line 156 is best formed from the matingsurface of the collimator to the respective detector. The collimatorholes are registered to the CZT detector pixels.

In the exemplary embodiment, the chamfered edges 150/152 are eachchamfered at an angle of approximately 45 degrees from the detectingface 128 to the horizontal line 156. As such, since both gamma cameras20 and 22 include the chamfered edges 150 and 152, when the gammacameras 20 and 22 are positioned in the L-mode, the detecting face 128of the first gamma camera 20 is at an approximate 45 degree angle fromthe detecting face 128 of the second gamma camera 22 as shown in FIG. 7.Moreover, when the first gamma camera 20 and the second gamma camera 22are in the L-mode configuration, a field-of-view 160 of the first gammacamera 20 extends to a field-of-view 162 of the second gamma camera 22.The field of views 160 and 162 are each illustrated by the cross-hatchedareas in the various figures. In the exemplary embodiment, thefield-of-view 160 is approximately touching without overlapping thefield-of-view 162 in this exemplary embodiment. In the exemplaryembodiment, the fields-of-view 160 and 162 are separated by a distancethat is less than 5 millimeters to enable lesions and/or tumors having adiameter that is less than approximately 5 millimeters to be imaged inthe L-mode configuration as shown in FIG. 7.

Referring again to FIG. 4, each of gamma cameras 20 and 22 also includeat least a third surface 164 and a fourth surface 166. Morespecifically, the second and third sides 122 and 124 are approximatelyperpendicular to the bottom and top surfaces. Chamfering both sides ofthe detector as discussed above, enables each gamma camera 20 and 22 tobe mounted in either the left-hand or right-hand position on the gantry12. More specifically, chamfering both 122 and 124 facilitatesfabricating gamma camera 20 substantially the same as gamma camera 22and therefore facilitates repair and replacement and production of gammacameras.

To improve patient comfort, each of gamma cameras 20 and 22 may alsoinclude a chamfered edge 168 shown in FIG. 6A. In the exemplaryembodiment, each gamma camera 20 and 22 includes the chamfered edge 168that is formed on the fourth side 126 of the gamma camera. As shown inFIG. 6A, the front chamfered edge 168 extends from the horizontalcenterline 156 to the second surface 130. In operation, the chamferededge 168 reduces patient discomfort by eliminating sharp edges that maycontact a patient during the imaging procedure. As such, the chamferededges 168 enable a patient to be positioned contacting the gamma cameras20 and 22 without the patient being jabbed or otherwise discomforted byrelatively sharp edges as is known in conventional gamma cameras.

FIGS. 8A-8E are perspective views of the molecular imaging system 10configured in various H-mode configurations wherein the gamma camera 20is approximately parallel to the gamma camera 22. For example, as shownin FIG. 8A, the gamma cameras 20 and 22 may be rotated to supportmedio-lateral and medial-lateral oblique imaging wherein the gammacameras 20 and 22 are disposed at the sides or angle to the anatomy ofinterest 24. Additionally, in the H-mode, the gamma cameras 20 and 22may be rotated to support cranio-caudal imaging wherein the gamma camera20 is disposed at the top of the anatomy of interest 24 and the gammacamera 22 is disposed at the bottom of the anatomy of interest 24.

As shown in FIG. 8B, the gamma cameras 20 and 22 may be rotated to imagea patient in a reclined position, for example, a patient lying on atable. In all modes described herein, the gamma cameras 20 and 22 andthe pressure plate are movable in an up and down configuration tosupport imaging patients either sitting, standing or reclining on atable. Moreover, as shown in FIG. 8B, the imaging system may include athird gamma camera 20. In the exemplary embodiment, the third gammacamera 21 is configured to perform imaging and to also to maintain thebreast within the imaging field of view of the first and second gammacameras 20 and 22.

As shown in FIG. 8C, the gamma cameras 20 and 22 may be rotated to imagea patient in a lateral view. Specifically, the patient is laying facedown on an imaging table and the breast extends through an opening inthe table such that the breast is disposed between the pair of gammacameras. As shown in FIG. 8D, the biopsy needle positioning device 82 isalso rotatable to perform a biopsy in this position. In the exemplaryembodiment, the imaging system may be configure to support medio-lateraland medial-lateral oblique imaging wherein the gamma cameras 20 and 22are disposed at the sides or angle to the anatomy of interest 24.Additionally, in the H-mode, the gamma cameras 20 and 22 may be rotatedto support cranio-caudal imaging wherein the gamma camera 20 is disposedat the top of the anatomy of interest 24 and the gamma camera 22 isdisposed at the bottom of the breast. As shown in FIG. 8E the gammacameras 20 and 22 may be turned parallel and side by side or turned outfor calibration and special anatomical positions. More specifically, thegamma cameras 20 and 22 may be arranged such that the imaging surfacesof each gamma camera are extending 180 degrees away from each other toenable a breast to be positioned on top of the gamma camera.

FIG. 9A is a perspective view of the gamma camera 20 shown in FIGS. 6Aand 6B and including at least one retractable retaining device or wall200. It should be realized that although FIG. 9A describes gamma camera20, that the retractable walls described herein may also be included inthe gamma camera 22. But for ease of discussion, only gamma camera 20 isdescribed and illustrated. As discussed above, when conventionaldetectors are configured for H-mode medial lateral or medial lateraloblique imaging, during imaging, gravity may cause a breast positioningerror such that a portion of breast including a lesion is out of thefield of view of the gamma detectors. Thus, the portion of breastoutside the gamma detectors field of view is not properly imaged. Assuch, in the exemplary embodiment, at least one of gamma cameras 20and/or 22 includes at least one retractable retaining device or wall tomaintain the anatomy of interest 24 in a field-of-view of the first andsecond gamma cameras 20 and 22.

As shown in FIG. 9A, the gamma cameras 20 and/or 22 includes a firstretractable wall 200 that is stored in and extends from a first recess202 that is formed in the housing 110. In the exemplary embodiment, thegamma camera 20 also includes a second retractable wall 204 that isstored in and extends from a second recess 206 formed in the housing 110and a third retractable wall 208 that is stored in and extends from athird recess 210 in the housing 110. The first recess 202 is definedbetween the inner wall of the first side 120 and the combination of thedetector array 140, the electronics device 142, and the collimator 144shown in FIG. 6A. More specifically, the housing 110 includes a space orrecess that is located between the detector portions and the internalsurface of the housing 110 that is sized to receive a retractable wall.In the exemplary embodiment, the first recess 202 includes an opening203 that is formed through the detecting face 128 proximate to the firstside 120, the second recess 206 includes an opening 207 that is formedthrough the detecting face 128 proximate to the second side 122, and thethird recess 210 includes an opening 211 that is formed through thedetecting face 128 proximate to the third side 124. During operation,the retractable walls are stored in the respective recesses and thenextended through a respective opening in the detector face. Theretaining function is also achievable using an accessory added foam orcloth retaining device.

As shown in FIG. 9B, in one embodiment, the retractable walls 200, 204,and 208 may each include a plurality of wall portions 212 that arecoupled together to form the respective retractable wall. Morespecifically, the portions 212 are slidably coupled together such thateach retractable wall may be fully retracted into the respective recessor fully extended from the respective recess. For example, in theexemplary embodiment, each retractable wall 200, 204, and 208 includesat least two portions 214 and 216 each having a width W. Thus when theretractable wall is fully retracted, each retractable wall has a widththat is approximately equal to W. In the exemplary embodiment, thedetector housing 110 has a width 220 that is greater than W to enablethe retractable walls to be fully stored within a respective recessformed within the housing 110. When the retractable wall is fullyextended, the width of the extended wall is approximately 2*W or 2W. Itshould be realized that if the retractable wall 200, 204, and/or 208includes n portions each having a width W, then the width of theretractable wall when fully extended is approximately n*W or nW.

In one embodiment, when the gamma cameras 20 and 22 are configured inthe L-mode configuration shown in FIGS. 1A and 1B, the retractable walls200, 204, and 208 are fully retracted into the respective recesses suchthat an outer edge 222 of each retractable wall 200, 204, and 208 issubstantially flush or level with the detecting face 128. In the L-modeconfiguration, the gamma cameras 20 and 22 may be repositioned withoutinterference from the retractable walls 200, 204, and 208. In the H-modeconfiguration shown in FIG. 6, at least some of the retractable walls202, 204, and/or 208 are at least partially extended. As shown in FIG.8A, at least some of the retractable walls 202, 204, and/or 208, whenfully extended, form a substantially square or rectangular anatomycapture region 230. The anatomy capture region 230 is selectively sizedto receive the anatomy of interest 24 therein. For example, the size ofthe anatomy capture region 230 may be increased to facilitate imaging alarger anatomy of interest by repositioning the gamma cameras 20 and 22and at least some of the retractable walls 202, 204, and/or 208 may bemore fully extended to form a larger anatomy capture region 230 tofacilitate imaging a more dense or larger anatomy of interest 24.Moreover, to facilitate imaging a smaller anatomy of interest 24, thegamma cameras 20 and 22 and at least some of the retractable walls 202,204, and/or 208 may be partially retracted into the housing 110 to forma smaller anatomy capture region 230 to facilitate imaging a smalleranatomy of interest 24.

Referring again to FIGS. 9A and 9B, in one embodiment, the retractablewalls 202, 204, and/or 208 are extended or retracted utilizing a manuallever 232. Optionally, the retractable walls 202, 204, and/or 208 may beextended or retracted utilizing a spring mechanism (not shown).Although, the retractable walls 202, 204, and/or 208 are illustrated astelescoping walls, it should be realized that the retractable walls 202,204, and/or 208 may also be embodied as detachable walls or fixed walls.Moreover, the retractable walls 202, 204, and/or 208 may be embodied asfolding walls or otherwise collapsing and adjusting walls. As such, theretractable walls 202, 204, and/or 208 form self-adjusting or adjustableside walls that facilitate restraining the anatomy of interest 24 infront of active area of the gamma cameras 20 and 22 when the molecularimaging system is configured in the H-mode mode.

FIG. 10A is schematic illustration of a portion of the gamma cameras 20and 22 in a first alignment. FIG. 10B is schematic illustration of aportion of the gamma cameras 20 and 22 in a second alignment. Asdiscussed above, each gamma camera 20 and 22 may generate a single imagethat is viewable by the operator. Specifically, the two images may beside-to-side images, images at forty-five degree angles, or top andbottom images, for example. To facilitate generating a single combinedimage from the two images, the gamma camera 20 is positioned in a knownalignment with respect to gamma camera 22.

Therefore FIG. 10A illustrates a cross-section of the collimators 144and 145 arranged in a first operational alignment and FIG. 10Billustrates a cross-section of the collimators 144 and 145, and thusgamma cameras 20 and 22 in a second operational alignment. As discussedabove, the gamma cameras 20 and 22 are adjustable to perform imaging inboth an L-mode configuration and an H-mode configuration. Moreover, eachgamma camera 20 and 22 may be separately aligned within eachconfiguration. More specifically, the gamma camera 20 may be offset fromthe gamma camera 22 in the X, Y, and/or Z direction while stillmaintaining the gamma cameras 20 and 22 in the L-mode or H-modeconfiguration. In the exemplary embodiment, the collimator 144 issubstantially aligned with the second collimator 145. Moreover, thefirst and second collimators 144 and 145 each have a resolution that isapproximately 5 millimeters at one-half mean breast thickness.

Referring again to FIG. 10A, the gamma camera 20, and thus collimator144 is approximately aligned with the gamma camera 22, and thuscollimator 145, in the Z-direction. More specifically, in thisembodiment, the septa 270 of collimator 144 are aligned with the septa272 of the collimator 145. In this configuration, the line of sight ofthe collimator 144 is collinear with the line of sight of the collimator145 such that the septa 270 and 272 are substantially perfectly aligned.As shown in FIG. 10A, one lesion 280 is substantially disposed betweentwo septa, whereas a second lesion 282 is disposed between two holes 284and 286 defined by the septa. In this case, the signal 290 output fromthe gamma camera 20 is combined with the signal 292 output from thegamma camera 22 to form a combined signal 294. The combined signal 294of the first lesion 280 represents the total response from both gammacameras 20 and 22 and is spread out over two pixels 296, e.g. theresponse is wide and flat. Whereas the combined signal 294 of the secondlesion 282 has a doubled response in half the pixels 296, therefore thecombined signal of the second lesion 282 is aliased, e.g. there is aphase mismatch between the frequency of the lesion 282 and the frequencyof the gamma cameras.

In another alignment configuration, shown in FIG. 10B, the gamma camera20, and thus collimator 144 is offset from the gamma camera 22, and thuscollimator 145, by approximately ½ pixel. More specifically, the gammacameras 20 and 22 are aligned such that the lesion 280 is positionedbetween an opening 284 on the collimator 144 and a septa 272 in thecollimator 145. Moreover, the lesion 282 is positioned between anopening 286 on the collimator 144 and a septa 272 in the collimator 144.During operation, the lines of sight of the collimators 144 and 145 are½ pixel displaced in an x-direction, a y-direction, or both an x and ydirection. In this case, a signal 300 output from the gamma camera 20 iscombined with a signal 302 output from the gamma camera 22 to form acombined signal 304. In this case, the combined signal 304, generated byaddition of the two images of the lesions, substantially equalizes thetranslation dependent MTF & DQE of the pixelated detector and produces adoubling of the effective Nyquist frequency of the single gamma camerasby themselves. Thus the dual gamma camera system of 2.5 mm pixelsfunctions similar to a system of 1.25 mm pixels. In the exemplaryembodiment, to optimize scan time without sacrificing detection ability,the far field resolution limit of the collimators is adjusted byadjusting the collimator height to 2.1 cm or the collimator aspect ratioto 10.

FIG. 11 is a side view of the imaging system configured to performcalibration. As shown in FIG. 11, the gamma camera 20 and the gammacamera 22 are positioned in the H-mode. Moreover, a flood source 23 isdisposed between the gamma cameras. During operation, the flood sourceis activated to perform to transmit light through the detectorcollimators to calibrate the gamma cameras. In this manner, theextrinsic calibration to verify the energy and sensitivity of each gammacamera is defined.

In various embodiments, the molecular imaging system 10, shown above isprovided by a method that includes positioning a pair of gamma camerasin an L-mode imaging configuration. A radiopharmaceutical may then beinjected into a patient and thereby into an anatomy of interest.Optionally, the radiopharmaceutical may be injected prior to positioningthe anatomy of interest or prior to positioning the gamma cameras. Theanatomy of interest is then immobilized between the pair of gammadetectors. As discussed above, in the L-mode configuration, the anatomyof interest rests on the gamma detectors. Moreover, an immobilizationforce may be applied to the anatomy of interest to facilitate retainingthe anatomy of interest in a substantially fixed position during theimaging procedure. An imaging scan of the anatomy of interest is thenperformed on the anatomy of interest immobilized between the pair ofgamma detectors.

The imaging operation results in a first image being generated by thefirst gamma camera and a different second image being generated by thesecond gamma camera. In the exemplary embodiment, the method alsoincludes combining the first and second image to form a combined image.One method of generating a combined image includes registering the firstgamma camera image with the second gamma camera image. Registration mayinclude locating a lesion on the first image and aligning the collimatoron the first gamma camera with a different second collimator on thesecond gamma camera such that the lesion is located between either apair of holes or a pair of septa on the collimators, e.g. the twocollimators are perfectly aligned. The resultant registered images maythen be combined by addition, geometric mean, error-weighted mean, oranother algorithm to form the combined image. Optionally, registrationmay include locating a lesion on the first image and aligning thecollimator on the first gamma camera with a different second collimatoron the second gamma camera such that the lesion is located between septaon the first collimator and a hole on the second collimator, e.g. thetwo collimators are offset by ½ pixel. The resultant registered imagesmay then be combined to form the combined image.

Thus, a molecular imaging system is provided, for example, configured asan upright stand-alone breast imaging system. The molecular imagingsystem includes two gamma cameras that are each adapted to render itsuperior performance for breast cancer management. The gamma cameras aresensitive in their field of view to the gamma rays emitted from theanatomy of interest and form an image of the areas of concentration ofan imaging agent. The gamma camera has reduced insensitive edges aroundthe field of view, reduced thickness, chamfers, and limited resolutioncollimators disposed to increase the sensitivity of imaging. The imagingsystem described herein therefore reduces background noise, reducesacquisition time, and improves the limits of cancer lesion detection.More specifically, the molecular imaging system described herein may beconfigured in an L-mode configuration for performing 3D localization andbiopsy of an anatomy of interest. The molecular imaging system may alsobe configured in the H-mode configuration. In the H-mode configurationadjustable or retractable retaining device or walls may be utilized tocorrect positioning errors for improved lesion detection. Moreover, thegamma cameras include chamfered edges to improve L-mode visibility anddecrease patient discomfort. The edges of the camera in contact with thepatient are rounded and or covered with foam to avoid injury to thepatient.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

What is claimed is:
 1. A gamma camera comprising: a housing a cadmiumzinc telluride (CZT) camera disposed within the housing, and at leastone retractable wall coupled to the housing and adapted to secure ananatomy of interest in a field-of-view of the gamma camera.
 2. The gammacamera of claim 1 wherein the housing comprises a chamfered edge toenable the gamma camera to contact a second gamma camera when the gammacamera is positioned in an L-mode imaging configuration.
 3. The gammacamera of claim 1 wherein the housing comprises a second chamfered edgethat is formed on an opposite side of the housing from the chamferededge.
 4. The gamma camera of claim 1 wherein the housing comprises alower surface, an upper surface, and a centerline disposed between theupper and lower surfaces, the a chamfered edge extending from thecenterline to the upper surface.
 5. The gamma camera of claim 1 whereinthe housing comprises a second chamfered surface extending from thecenterline to the lower surface.
 6. The gamma camera of claim 1 whereinthe housing comprises a detecting surface and an opening extendingthrough the detecting surface, the retractable wall configured to extendthrough the opening.
 7. The gamma camera of claim 1 further comprising asecond retractable wall coupled to the housing and adapted to secure ananatomy of interest in the field-of-view of the gamma camera.
 8. Thegamma camera of claim 1 further comprising a different secondretractable wall coupled to the housing, the second retractable wallbeing positioned perpendicular to the retractable wall and configured tobe fully retracted into the housing in a first imaging mode and extendfrom the housing in a different second imaging mode.
 9. The gamma cameraof claim 1 wherein the cadmium zinc telluride (CZT) camera comprises apixilated solid state detector.
 10. The gamma camera of claim 1 whereinthe housing comprises a first side, a second side disposed opposite tothe first side, a third side, a fourth side, the first and second sidescomprising a chamfered surface to enable the gamma camera to contact asecond gamma camera.
 11. The gamma camera of claim 1 further comprisinga collimator including a plurality of holes, each collimator hole beingregistered with a respective pixel formed on the CZT detector.
 12. Thegamma camera of claim 1 further comprising a manual lever coupled to theretractable wall and configured to extend and retract the retractablewall.
 13. The gamma camera of claim 1 wherein the cadmium zinc telluride(CZT) camera comprises a solid state detector, an electronics devicecoupled to the solid state detector, and a collimator disposed on thesolid state detector.
 14. A gamma camera comprising: a housingcomprising a chamfered edge to enable the gamma camera to contact adifferent second gamma camera when the gamma camera is positioned in anL-mode imaging configuration; a cadmium zinc telluride (CZT) cameradisposed within the housing, and at least one retractable wall coupledto the housing and adapted to secure an anatomy of interest in afield-of-view of the gamma camera.
 15. The gamma camera of claim 14wherein the housing comprises a second chamfered edge that is formed onan opposite side of the housing from the chamfered edge, the chamferededge and the second chamfered edge each extending from a centerlinedisposed between an upper and lower surface of the housing to thehousing upper surface.
 16. The gamma camera of claim 14 furthercomprising a different second retractable wall coupled to the housing,the second retractable wall being positioned perpendicular to theretractable wall and configured to be fully retracted into the housingin a first imaging mode and extend from the housing in a differentsecond imaging mode.
 17. A method of fabricating a gamma camera, saidmethod comprising: fabricating a housing that includes a first side, asecond side, a third side, a fourth side, and an opening defined by thefirst, second, third, and fourth sides; installing a cadmium zinctelluride (CZT) camera within the housing opening, and installing atleast one retractable wall within the housing, the retractable walladapted to secure an anatomy of interest in a field-of-view of the gammacamera.
 18. The method of claim 17 further comprising chamfering atleast one of the housing sides to enable the gamma camera to contact asecond gamma camera when the gamma camera is positioned in an L-modeimaging configuration.
 19. The method of claim 17 further comprisingfabricating the housing to include a recess that is formed between aninterior surface of the housing and the CTZ camera, the retractable wallbeing configured to be stored in the recess in a first mode of operationand extend from the recess in a different second mode of operation. 20.The method of claim 17 further comprising installing a retractable wallincluding a plurality of telescoping portions within the housing, theretractable wall adapted to telescope from the housing to secure ananatomy of interest in a field-of-view of the gamma camera.